1. Field of the Invention
The present invention relates generally to a turbomachine, and more specifically for a labyrinth seal in a turbomachine.
2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
A labyrinth seal is a mechanical seal that fits around an axle to prevent the leakage of oil or other fluids. A labyrinth seal is composed of many straight grooves that press tightly inside another axle, or inside a hole, so that the fluid has to pass through a long and difficult path to escape. Sometimes screw threads exist on the outer and inner portion. These interlock, to produce the long characteristic path which slows leakage. For labyrinth seals on a rotating shaft, a very small clearance must exist between the tips of the labyrinth threads and the running surface.
Turbines use labyrinth seals due to the lack of friction, which is necessary for high rotational speeds. Labyrinth seals are used in turbo-machinery designs to control internal flow leakage and maintain desired pressures for internal cavities. A labyrinth seal typically includes two or more teeth or knife edges that form a seal with an opposed surface. In some labyrinth seals, the knife edges rotate while in other labyrinth seals the knife edges are stationary.
On occasions, labyrinth seals experience high cycle fatigue (HCF) due to resonance, coincidence and flutter instability. The fluid leakage across the gaps of the knife edges will induce vibrations within the teeth and cause them to break off. Common design fixes to prevent vibrations of labyrinth seals is to add damping. However, that may not be possible for a stationary seal, should a split-ring damper be used.